通过作者查论文: Seong Ho Choi

文章题目页数

作者: Byung Hyun Lee, Min Chul Kim, Seong Ho Choi, Yong Keun Lee
摘要: We developed new calcium phosphate bone substitute material, amorphous calcium polyphosphate. The new material is synthesized by a cement-like slif-setting reaction with calcium phosphate glass, basic materials and water. In this study, we prepared with CPG, Na2CO3 and NaOH solution. When they are mixed together, amorphous phase was precipitated. The precipitated amorphous phase consisted of polyphosphate chains condensed with Na ions released from Na2CO3 and NaOH. When the amorphous calcium polyphosphate dissolves, inorganic polyphosphates are released into the medium. The inorganic polyphosphates as the dissolution product inducted the calcification of the osteoblast cells. Therefore, in animal test, the new bone formation in rat calvarial defects treated with the new material was significantly higher than sham-surgery control group, especially in the initial stage. The amorphous calcium polyphosphate was biocompatible and bioresorbable and promoted the new bone formation.
209
作者: Min Chul Kim, Byung Hyun Lee, Kyoung Nam Kim, Kwang Mahn Kim, Seong Ho Choi, Chong Kwan Kim, Racquel Z. LeGeros, Yong Keun Lee
摘要: A numerous techniques have been applied to fabricate three-dimensional scaffolds of high porosity and surface area. And X-ray micro computed tomography can be used studying the architecture of scaffold. In this study, we fabricated three-dimensional macroporous scaffold by polymeric sponge method using calcium phosphate glass. Calcium phosphate glass slurry was prepared by dissolving the glass powder in water polyvinyl alcohol, polyethylene glycol and dimethyl formamide. Reticulated polyurethane sponges were used as a template and were coated with the prepared slurry by infiltration technique several times. Sintering at 950oC exhibited dense microstructure as well as entire elimination of organic additives. By repeating the coating and sintering process, it was possible to decrease the pore size and be thick the strut of the structure. The unique feature of the micro computed tomography is that the three dimensions computed reconstruction can be sliced along any direction to gain accurate information on the internal geometric properties and structural parameters of scaffold. Porosity, surface area per unit volume and mean thickness of strut were evaluated through imaging and computer software of scaffold scan data.
1087
作者: Byung Hyun Lee, Min Chul Kim, Kyoung Nam Kim, Kwang Mahn Kim, Seong Ho Choi, Chong Kwan Kim, Racquel Z. LeGeros, Yong Keun Lee
摘要: In preliminary ageing test, the cement using only calcium phosphate glass as power phase cracked with 1 day in simulated body fluid because of high dissolution rate of the cement. We added 30 wt% of either β-TCP or HA to 70 wt% calcium phosphate glass as powder phase to control the dissolution rate of the cement and performed in vitro ageing test in simulated body fluid by dynamic protocol as well as static protocol to confirm the possibility of controlling. Adding either β-TCP or HA to the cement increases the setting time and decreases the compressive strength. In dynamic assay, the pH of extract is maintained over 7. However, pH decreased to around 5 in static assay. Therefore, weight loss by static protocol continuously increased for 14 days, while weight loss by dynamic protocol almost saturated. In XRD patterns of ageing cements, CaO peaks appeared. CaO peak was maximized most lately in dynamic assay of the cement adding HA and within 7 days, the cement adding HA showed higher weight loss. It is indicated that CaO formed in surface of the cement hinder the dissolution of the cement. In addition, compressive strength increased when the CaO peak was maximized.
861
作者: Seong Ho Choi, D.H. Baik, C.S. Kim, Chong Kwan Kim, Kyoung Nam Kim, Kwang Mahn Kim, Racquel Z. LeGeros, Yong Keun Lee
摘要: The purpose of this study was to compare the bone regenerative effect of calcium phosphate glass and glass-ceramics in the system of CaO-CaF2-P2O5-MgO-ZnO, which is already reported that promoted the bone-like tissue formation in vitro and formed new bone in Sprague-Dawley rats. We prepared calcium phosphate glass and glass-ceramics with Ca/P ratio of 0.6 using the system CaO-CaF2-P2O5-MgO-ZnO and subsequently milled to 400 µm. 4×4 mm 1-wall intrabony defects of six beagle dogs were surgically created and used in this study. 8 weeks after transplantation of the prepared calcium phosphate glass and glass-ceramics in the experimental group 1 and 2, respectively, the animals were sacrificed. No root resorption or ankylosis were observed in all groups. It can be examined that the prepared glass-ceramics were more effective in alveolar bone regeneration with statistical signigicant difference. In cementum regeneration, both the prepared glass and glass-ceramics showed significantly different effect. However, there were no statistical significant difference neither in glass nor glass-ceramics in the amounts of junctional epithelium migration and connective tissue adhesion. Further study is required to control the flowability as well as reduce the absorption rate in vivo.
957
作者: Yeon Ung Kim, Min Chul Kim, Kyoung Nam Kim, Kwang Mahn Kim, Seong Ho Choi, Chong Kwan Kim, Racquel Z. LeGeros, Yong Keun Lee
摘要: This study presents the manufacture of macroporous hydroxyapatite scaffolds with a small amount of calcium phosphate glass powder as sintering additives. Hydroxyapatite slurry was prepared by suspending the hydroxyapatite and glass powder in water. Polyurethane sponge was used to produce highly macroporous scaffolds. The rheological characteristic of the slurry was measured to identify the effect of adding calcium phosphate glass powder into hydroxyapatite slurry. Sintered scaffolds could be repeatedly coated to improve mechanical properties. Scaffolds prepared by single and double replication cycle process were characterized by density, porosity and compressive strength measurements by increasing amount of the calcium phosphate glass powder to the hydroxyapatite slurry, viscosity by increased more than same amount of pure hydroxyapatite, and the capillary force was similar to pure hydroxyapatite slurry. The compressive strength of the macroporous hydroxyxapatite scaffold containing the calcium phosphate glass powder showed higher value than that of pure hydroxyapatite at single replication cycle. SEM demonstrated that the microstructure of the scaffold became denser with the introduction of the calcium phosphate glass powder. The pore struts were thicker as replication cycle was increased.
313
作者: D.H. Min, M.J. Kim, J.H. Yun, C.S. Kim, Yong Keun Lee, Seong Ho Choi, Kyoung Nam Kim, Chong Kwan Kim
摘要: This study evaluated periodontal repair and biomaterial reaction following implantation of a newly fabricated calcium phosphate block bone with chitosan membrane on the regeneration of 1-wall intrabony defects in the beagle dogs. The surgical control group received a flap operation only, while the experimental group I was treated with a chitosan nonwoven membrane only and the experimental group II was treated with a chitosan nonwoven membrane and a calcium phosphate block bone. The subjects were sacrificed 12 weeks after surgery and a comparative histometric analysis was done. No root resorption or ankylosis were observed in the experimental group. Mann-Whitney U test showed that the experimental group II produced statistically significant higher gain in connective tissue adhesion, new cementum regeneration and new bone formation. Based on histological results, the calcium phosphate block bone successfully functioned as a osteoconductive scaffold for invading cells of host.
851
作者: Yeon Ung Kim, Byung Hyun Lee, Min Chul Kim, Kyoung Nam Kim, Kwang Mahn Kim, Seong Ho Choi, Chong Kwan Kim, Racquel Z. LeGeros, Yong Keun Lee
摘要: The objective of this study was to produce a macroporous hydroxyapatite(HA) scaffold with high strength by controlling the size of HA particles as well as cooling rate from the sintering temperature. Macroporous polyurethane sponge was employed as template to manufacture the macroporous HA scaffolds. Particle sizes of HA powders selected in this study were 4 µm and 7 µm. They were dispersed in distilled water with organic additives and infiltrated into polyurethane sponge. After drying and sintering at 1300oC, cooled down to room temperature slowly to prevent microcracking either 1oC/min or 3oC/min. Density, porosity and compressive strength were measured with different particle size and cooling rate. Both density and compressive strength were increased with decreasing particle size or cooling rate, while porosity was not related to.
1047
作者: Min Chul Kim, Kyoung Nam Kim, Kwang Mahn Kim, Seong Ho Choi, Chong Kwan Kim, Racquel Z. LeGeros, Yong Keun Lee
摘要: The development of phosphate glasses for use in orthopaedic implants has attracted much interest because their chemical and physical properties make them suitable for use as bone-bonding materials. We prepared various compositions of CaO-P2O5-MO or CaO-P2O5-M2O (M: K, Li, Na, Mg, Zn) glasses to measure ion release, solubility and bioactivity. The compositions with (Ca,M)/P molar ratio 0.6 were fixed P2O5 mol% content at 45.45 mol%, and varying MO or M2O mol% at 10, 20 and 30 mol%. Ca2+ ion release properties were investigated in 0.1M potassium acetate with pH 6 at 37oC by immersing 50 mg of powder into 100 ml of acidic buffer solution. The highest and lowest extent of released Ca2+ ion was observed for composition with 10 mol% of K2O and 30 mol% of MgO, respectively. The weight loss in distilled water at 37oC was measured. Solubility increased with decreasing CaO content, but decreased with increasing MgO content. Bioactivity in the simulated body fluid at 37oC was measured.
513
作者: Hyun Ju Moon, Racquel Z. LeGeros, Kyoung Nam Kim, Kwang Mahn Kim, Seong Ho Choi, Chong Kwan Kim, Yong Keun Lee
摘要: The purpose of this study was to compare the bone regenerative effect of calcium phosphate glass according to the particle size in vivo. We prepared two different sizes, that is 400 μm and 40 μm, of calcium phosphate glass powder using the system CaO-CaF2-P2O5-MgO-ZnO. Critical-sized calvarial defects were created in 60 male Sprague-Dawley rats. The animals were divided into 3 groups of 20 animals each. Each defect was filled with a constant weight of 0.5 g calcium phosphate glass powder mixed with saline. As controls, the defect was left empty. The rats were sacrificed 2 or 8 weeks after postsurgery, and the results were evaluated using histological as well as histomorphometrical studies. The particle size of the calcium phosphate was crucial; 400 μm particles promoted new bone formation, while 40 μm particles inhibited it because of severe inflammation.
165
作者: Ui Won Jung, S.J. Chang, Seong Ho Choi, C.S. Kim, Jung Kiu Chai
摘要: This study evaluated the effects of mixture of fibrin-fibronectin sealant system(FFSS) and calcium carbonate(CC) in periodontal intrabony defects. Thirty six sites with two or three wall intrabony defect were used. 14 defects treated with periodontal flap surgery were assigned as the control group. 11 defects treated with CC implantation were designed as experimental group 1 and 11 defects, treated with CC and FFSS implantation as experimental group 2. The control and experimental groups all achieved statistically significant improvements in probing depth and clinical attachment level from the baseline (P<0.01). In mean postsurgery probing depth and gingival recession reduction, there were no statiscally significant differences between the experimental groups and the controls. However, mean postsurgery clinical attachment levels of both experimental groups improved significantly more than that of the controls. As a result, we suggest that mixture of FFSS and CC can be used effectively in intrabony defect as osteoconductive materials.
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